Integrated circuits having a logic circuit and reception means are known and are now used to an increasing extent in the form of so-called RFID (Radio Frequency Identification) transponders for identification purposes in the service sector or in the fields of logistics, trade or manufacturing. However, also systems utilizing lower frequencies (below 800 MHz) are used.
A transponder normally includes a semiconductor chip for storing data, which may be programmable and rewritable, and an antenna being adapted for the relevant frequency band (e.g. US-UHF: 902-928 MHz, Europe: 863-868 MHz, ISM: 2.4-2.483 GHz). A common RFID system comprises RFID transponders, reading devices having a system antenna providing a bi-directional (data) communication between the transponders and the reading devices.
In general, there is a distinction between active transponders and passive transponders. Active transponders are provided with an energy supply of their own while passive transponders receive the power necessary for operation from the high frequency signals, which are also used for communication.
US 2004/0131897 A1 discloses an RF transponder which combines the features of active and passive transponders. The transponder of US 2004/0131897 A1 comprises an electronic circuit, an RF antenna and a battery, wherein the electronic circuit is connected to the battery and thus receives energy from the battery upon reception of RF energy by the antenna which closes a switch between the electronic circuit and the battery and enables an electric connection between the battery and the electronic circuit.
The known transponder systems are limited in their purpose since the transponders only provide a functionality of identification and data communication between the transponders and the reading devices.